Wrist actigraphy may be employed for initial diagnostic of sleep-related pathologies. Actigraphy may support large-scale, population-level sleep research by facilitating inexpensive, unobtrusive measurement across a wide range of circumstances and locations and may provide an opportunity for longitudinal and repeated measures. Wrist actigraphy may be useful for estimating total sleep time and wakefulness after sleep onset. However, wrist actigraphy has at least two major limitations: 1) sleep stages may not be discriminated; and 2) specificity (correctly assigned wake epochs) may be very low. These limitations may be expected because discrimination between N1 to N3 stages of sleep and quiet wakefulness may not be feasible based only on the wrist movements.